Spark-plug



W. A. LATSHAW.

SPARK PLUG.

APPLICATION FILED NGV, 9. 1911.

Patented J 11116 3, 1919.

W L efiishaw.

WILEY ALBERT LATSHAW, OF CLARION, MICHIGAN.

SPARK-PLUG.

Application filed November 9, 1917. Serial No. 201,142.

To all whom it may concern:

Be it known that I, WILEY ALBERT LAT- SHAW, a citizen of the United States, and a resident of Clarion, in the bounty of Charlevoix and State of Michigan, have invented a certain new and useful Improvement in Spark-Plugs, of which the following is a specification.

The present invention relates to spark plugs, and more particularly to that type provided with means for sighting the spark at the outer ends of the plug for the purpose of testing the ignition circuit without removing the plug from the cylinder head.

An object of the present invention is to provide a spark plug of this character which comprises relatively few parts; which supports a sight tube without contact with metallic parts; which is of substantially the same size of the ordinary spark plug; which is provided with means admitting of the easy and ready adjustment of the spacedapart electrode sections; and which is proviged with means for protecting the sight tu e.

The above, and various other objects and advantages of this invention will be in part described, and in part understood, from the following detailed description of the present preferred embodiment, the same being illustrated in the accompanying drawing whereinzf Figure 1 is a side elevation of a spark plug constructed according to the present invention.

Fig. 2 is a cross section through the upper end of the same taken substantially on the line 22 of Fig. 1, the view being enlarged.

Fig. 3 is an enlarged longitudinal section taken centrally through the spark plug of this invention.

Referring to this drawing, designates the shell or cup of the spark plug which is provided in the usual manner with a base flange near its lower end and a depending externally threaded portion adapted for engagement in the head of a cylinder. The shell 10 is provided with a fixed electrode 11 upon its lower end which extends inwardly toward the central axis of the plug.

The shell 10 is provided intermediate its ends, with an internal annular shoulder 12 adapted to support a barrel 13 of porcelain or other suitable heat and electric non-conducting material. The barrel 13 is provided near its lower end with an annular exterior shoulder adapted to seat upon the shoulder 12,- and a gasket or packing Washer 14 is interposed between the shoulders. The upper end of the barrel 13 is reduced in diameter and the upperend of the shell 10 is internally screw-threaded as shown. A gland nut 15 is fitted about the upper end of the barrel l3 and is screwed into the upper end of the shell 10, a packing washer or gasket 16 being interposed between the lower end of the gland nut 15'and the upwardly facing shoulder 17 formed exteriorly of the barrel 13 at the base of its reduced portion. The gland nut 15 retains the barrel 13 within the shell 10. he upper extremity of the barrel 13 is further reduced to provide a stem portion 18 forming an annular passage or way in the upper end of the barrel, and the upper end of the gland nut 15 is counterbored to provide a corresponding annular channel or seat opposite the stem 18. A fibrous packing ring 19 substantially U-shaped in cross section is seated in the annular channel or way formed between the stem 18 of the barrel and the upper end of the gland nut 15, the fibrous packing ring being formed of asbestos or other suitable material. A transparent cylinder 20, formed preferably from glass, is seated at its lower end within the U-shaped packing ring 19 and, is held thereby from contact with the barrel 13 and the gland nut 15. The upper end of the cylinder 20 is closed by a plug 21 in the form of a head which projects into the upper end of the cylinder 20 to a slight extent and which is provided with an overhanging flange engaging across and extending beyond the upper edge of the cylinder. This head or plug 21 is preferably formed from vulcanized rubber or fiber which is heatnon-conducting and electric-non-conducting. The head or plug 21 is provided upon its upper side with an upstanding bolt or projection about which is fitted a collar 22 of metal or the like, and a plurality of screw rods 23 pass downwardly through the outstanding flange portion of the collar 22 and through the flange portion of the head 21, and have their lower screw-threaded ends engaged in threaded relation in suitably formed apertures in the upper end of the gland nut 15. The screw rods 23 are adapted to bind the Patented June 3, 1919.

I head 21 against the top of the tube 20 and bind the latter against the U-shaped packing rin 19.

The electrode 11 constitutes the grounded I electrode, and the line wire electrode comprises a pair of rod sections 24 and 25 which are carried respectively in the barrel 13 and the head 21. The inner line electrode section 24 passes axially through the barrel 13 and is provided with a collar or enlargement 25' near its lower end adapted to engage the lower extremity of the barrel 13. The upper end of the sect-ion'24 is screw threaded and receives thereover a packing washer .26 and a clamping nut 27, the latter binding the washer 26 against the upper end of the stem 18 of the barrel to seal the section 24 in thebarrel. The upper extremity of the electrode section 24 is dished or cupped to provide a depressed sparking point or terminal while the adjacent inner end of the section 25 is in the form of a cone 29 which is of such size that it may fit into the depression 28. The section 25 is relatively short, and is threaded through the head 21. The outer end of the section 25 has a cut therein adapted to receive the bit of a screw driver or the like for turning the section 25 and adjusting the same longitudinally through the head 21 toward and from the adjacent extremities of the fixed section 24.

A look nut 30 is threaded upon the upper end of the section 25 and is provided at its under side with a packing washer 31 which binds against the upper end of the bulk of the head 21 for locking the stem 25 in the head 21 and sealing the stem therein. It will be noted from Fig. 3 particularly, that the upstanding portion of the head 21 is of a height greater than that of the collar 22 to prevent electrical connection between the collar 22 and the binding nut 30. The outer' stem section 25 is also provided with a binding nut 32 of the usual type adapted to clamp a terminal 33 of a high tension wire about the stem section 25 and between the lock nut 30 and the binding nut 32.

The operation of the plug is apparent, for when the circuit is closed through the same the spark occurs not only at the inner or lower terminals of the electrodes 11 and 24,

' but also between the adjacent spaced-apart ends of the electrode sections 24 and 25 which are located with in the transparent tube 20. The transparent tube 20 is held from contact with the metal parts of the plug by the fibrous head 21 and the fibrous packing ring 19. The screw rods 23 firmly hold the head 21 upon the cylinder or tube 20, and bind the latter firmly upon the barrel 13 and within the gland nut 15. The size of the spark may be regulated by the adjustment of the electrode section 25 partially within the upper through the head 21, the section 25 being locked in adjusted position by tightening the lock nut 30 down upon the head 21 and if desired the section 25 may be moved inwardly for seating the cone end 29 thereof in the depression or cup 28 in the section 24 to eliminate the spark gap in the upper part of the tube.

In cleaning the spark plug, the clamp nut 15 may be disconnected from the shell 10 and it will carry electrode 25, tube 20 and their companion parts with it, leaving the upper end of the electrode 24 exposed for cleaning.

It is of course understood that various changes and modifications may be made in the details of construction and design of the above specifically described parts of the invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims.

I claim 1. In a spark plug, the combination of a shell, a barrel fitting in the shell, a gland nut carried upon the upper end. of the shell and engaging the barrel to bind the latter in the shell, a glass cylinder fitting upon the upper end of the barrel, a U-shaped packing ring fitting about the lower end of the cylinder and against the barrel, a fibrous head fitting upon the outer end of the glass cylinder, screw rods connecting the head to the gland nut for binding the head and the barrel against the opposite end of the gland cylinder, 2. fixed electrode section in the barrel, a movable electrode section arranged within the head and adapted for adjustment toward and from the upped end of the fixed electrode section, and means for locking the a gland nut connected to the shell and bindmg said barrel therein, a substantially U- shaped non-heat conducting packing ring, end of said gland nut and about the upper 6 Id of said barrel, a transparent tube having its lower end seated between the upstanding portions of 7 said U-shaped packing ring, a non-conducting head mounted upon the upper end of said tube and having an annular flange formed thereon and a plurality of screw rods ex-- tending through said flange and threaded into said flange nut.

3. In a spark plug, the combination, of a shell, a porcelain barrel carried by said shell, a gland nut connected to the shell and binding said barrel therein, a substantially U-shaped non-heat conducting packing ring partially within the upper end of said gland nut and about the upper end of said barrel, a transparent tube having its lower end seated between the upstanding portions of said U-shaped packing ring, a non-conneoaeae a. central electrode carried by said non-com ducting head for adjusted movement toward 1a or from said cupped ends, the inner terminal of said adjustable electrode being substantia'lly cone shaped for seatlng in the cupped end of said stationary electrode WILEY ALBERT LATSHAW. 

